Physiological age of female blood-sucking midges (Diptera, Ceratopogonidae) in the south of Tyumen oblast

Abstract

Despite the fact the fact that biting midges (Diptera, Ceratopogonidae) are abundant blood-sucking insects in a number of areas of Siberia and the Far East, their biology in Russia and abroad is poorly studied. The objective of our research was physiological age of female midges in the subzone of southern taiga of Tyumen Oblast. Physiological age of female midges was determined using the method of V. P. Polovodova and T. S. Detinova, suggested for mosquitoes, modified for midges, in relation to the number of the yellow bodies – enlarged ovarioles. The conducted studies focused on physiological age of females of three species of midges of the subgenus Avaritia (Culicoides punctatus, C. fascipennis, C. grisescens), which occur in the forest zone of the southern taiga subzone. The species are abundant blood-sucking insects. Mostly, they complete one gonotrophic cycle, but by the end of the season, the number of females which had laid eggs twice reached 20–30%. Part (10–22%) of the female population does not succeed in completing even a single gonotrophic cucle. In spite of colder weather in the end of summer, a rejuvenation of the population was observed, which occured due to death of physiologically old females. Comparison of changes in number and age composition of females allows us to state that the first two species have two, and the third – one generation during a season. Determination of physiological age of females or the number of gonotrophic cycles they complete, and therefore, the extent of their biting, is a subject of not only theoretical but also practical interest for assessing the epidemiological situation in the areas where midges are vectors of a number of infectious and invasive diseases, such as tularemia, onchocerciasis, bluetongue virus or febris catarrhalis ovium, and Schmallenberg virus. This indicates the relevance of studying density of population vectors of infections. In the Russian Federation, such research unfortunately has only been conducted within the scope of narrow studies, and only in certain regions.